1. Field of the Invention
The present invention relates to snap-together modular ventilation fan assemblies for electronics enclosures.
2. Description of Related Art
Modular ventilation fan assemblies, sometimes called fan tray assemblies (or more briefly, “fan trays”) are used for mounting ventilation fans to electronics enclosures, such as computer enclosures. Conductive enclosures are used to contain electromagnetic interference (EMI) generated by electronic equipment, and ventilation fans are often used for thermal control of their enclosed interior spaces. The fan tray provides for convenient mounting of one or more ventilation fans to the electronics enclosure while maintaining the EMI-shielding integrity of the enclosure. The fan tray may also provide a convenient location for mounting a control circuit for the ventilation fan or fans in the fan tray.
The ventilation fan itself is usually a modular unit that includes a rotor and a motor encased in a plastic housing. As such, it does not provide EMI shielding and may itself be a source of EMI. Fan trays therefore typically provide metal grills on opposite sides of the fan to electromagnetically isolate the ventilation fan from the environment outside of the fan tray, while allowing for the passage of air through the fan tray. At the same time, the metal grills and sheet metal walls of the fan tray maintain electromagnetic isolation for the interior of the electronics enclosure and serve as part of the wall thereof.
Fan trays are often mounted to the electronics enclosures using a pair of opposing side rails that engage corresponding rails in the electronics enclosure. The fan tray may be mounted to, and removed from, the enclosure by sliding the tray along these rails. The fan tray may be secured to the enclosure using a screw or like fastener after being slid into place along the rails. As modular assemblies, prior art fan trays facilitate assembly and repair of electronics enclosures, particularly when a fan control circuit is included in the fan tray.
However, prior art fan trays are subject to various shortcomings. They are typically assembled from sheet metal components and fastened together using screws or like fasteners. Screws are also used to fasten assembled fan trays to electronics enclosures. The use of screws or like fasteners increases assembly and removal time, and increases the number of tray components. The use of these prior art fasteners can also damage the fans and/or take the fan trays out of industry standards. For example, if too much pressure is applied at the fan edges, the fans can be damaged. By contrast, if too little pressure is applied at the fan edges, the fans in the fan trays produce a high amount of acoustical noise that can take the fan trays out of industry standards (e.g., standards on restricting the amount of noise produced). All of these factors can add substantially to the cost of fan trays, as well as create inconveniences for users.
It is therefore desirable to provide a fan tray assembly that overcomes these and other shortcomings of prior art fan tray assemblies, while retaining their advantages. More specifically, it is desirable to provide a fan tray assembly that has features in which airflow is not impeded, acoustical noise is reduced, assembly and disassembly is simplified, and cost of manufacturing is reduced.